This invention relates to plumb bobs.
Plumb bobs having a marking capability are known. Such bobs contain either chalk or a marking fluid which, when the bob is used, mark the point where the plumb line has been set. Although such bobs can be used over or on relatively clean, hard-surfaced materials such as concrete, where the chalk or liquid mark will be easily visible, they are less useful over such surfaces as dirt or sand, where the mark may be hard to see or insufficiently durable.
A plumb bob that can leave a visible, long-lasting mark on any type of surface or material is desirable in view of the limitations of existing plumb bobs.